Abstract: To explore the safety of echelon—use lithium—ion batteries for energy storage, this article studied the thermal runaway propagation characteristics of large—capacity energy storage echelon—use lithium—ion battery modules under two abusive conditions of external heating and overcharging by modeling actual energy storage site. Under external heating conditions, the induced heat that triggers the thermal runaway of lithium—ion batteries comes from outside the battery. The maximum temperature of the thermal runaway battery in the module is 295.6 ℃, and the maximum mass loss rate of the thermal runaway battery is 18%. It presents a two—way thermal runaway propagation, with a maximum propagation speed of 0.022 mm/s and a total thermal runaway propagation time of 9 316 s. Under overcharging conditions, the induced heat that triggers thermal runaway in lithium—ion batteries mainly comes from within the battery. The maximum temperature of the thermal runaway battery in the module is 499.5 ℃, and the maximum mass loss rate of the thermal runaway battery is 21.5%. The total propagation time of the thermal runaway is only 827 s. Compared to the thermal runaway triggered by external heating, the thermal runaway temperature triggered under overcharging conditions is higher, and the propagation time of thermal runaway is shorter. Therefore, the risk of thermal runaway fire and explosion in lithium—ion batteries caused by overcharging is greater.

Key words: lithium—ion batteries module, echelon use, external heating, overcharge, thermal runaway